Upregulation of CD47 in regulatory T cells in atopic dermatitis

Purpose: Regulatory T (Treg) cells are key modulators in the immune system. Recent studies have shown that atopic dermatitis (AD) patients have higher numbers of Treg cells; however, little is known about the specific phenotype and function of Treg cells in AD. Materials and Methods: To identify differentially expressed proteins in peripheral induced Treg cells in AD and naturally derived Treg cells in normal controls, CD4⁺CD25⁺ Treg cells were isolated from thymus tissue of normal mice and the spleens of AD mice. Membrane proteins were extracted, and quantitative proteomics labeling with Tandem Mass Tags (TMT) was performed, followed by one-dimensional liquid chromatography/tandem mass spectrometry analysis. Results: Using TMT labeling, we identified 510 proteins, including 63 membrane proteins and 16 plasma membrane proteins. CD47 was one of the upregulated proteins in Treg cells in AD spleens. Although CD47 was expressed in all CD4⁺ and CD8⁺ T cells, a significantly higher expression of CD47 was observed in the Treg cells of AD mice and AD patients than in those of normal mice and healthy controls. Furthermore, Treg cells from the spleen showed a significantly higher expression of CD47 than those from the thymus. Conclusion: We found that CD47 is highly expressed in the Treg cells of AD mice, particularly in the spleen. Based on our results, we propose that CD47^high Treg cells are likely induced Treg cells and that upregulated CD47 in the Treg cells of AD patients may play a role in the increased population of Treg cells in AD.